Artificial ice nuclei generator

ABSTRACT

In this generator, a nose cone is mounted in the inlet of a cylindrical combustion chamber. Openings in the cone&#39;&#39;s surface admit combustion air into the chamber, and slots around the cone&#39;&#39;s base establish a boundary layer airflow along the chamber wall. A fuel injection nozzle mounted in the apex of the nose cone sprays an acetone solution of a silver iodide-sodium iodide complex into the chamber, where the resulting vapor is ignited. The combustion temperature and hence the vaporization of the complex is controlled by a choke that terminates the combustion chamber. A shell mounted around the combustion chamber ducts preheated air into a heat-insulated, choked chamber where the air quenches the growing nuclei. The resultant dispersion is expanded by a diverging tail portion of the shell. A housing mounted around the shell ducts cool air into the expanding dispersion. A diverging tail portion on the housing deflects outwardly the air flowing along the housing.

Waited Mates atent Patten 1 lFeib. 29, WW2

[54] ARTKIFHCEAL HCE NUCLIEII GENERATOR Primary ExaminerM. Henson Wood, Jr. Assistant Examiner-Thomas C. C ulp, .l r.

[72] Inventor: Bradley T. Patten, 10460 S.W. 44th Ter- Atmmey David Robbins and Alvin JL Englen race, Miami, Fla. 33165 22 Filed: Sept. 4, 1970 [57] ABSTRACT In this generator, a nose cone is mounted in the inlet of a c lin- [211 Appl' 69694 drical combustion chamber. Openings in the cones suri ace admit combustion air into the chamber, and slots around the [52] U.S. Cl ..239/1l4 cones base establish a boundary layer airflow along the [51] int. Cl l .Atllg 115/00 chamber wall. A fuel injection nozzle mounted in the apex of [58] Field at Search ..239/2, 14; 244/136 the nose Cone pr y n acetone Solution of a silver iodidesodium iodide complex into the chamber, where the resulting vapor is ignited. The combustion temperature and hence the vaporization of the complex is controlled by a choke that terminates the combustion chamber. A shell mounted around the [56] References Cited combustion chamber ducts preheated air into a heat-insw lated, choked chamber where the air quenches the growing UNITED STATES PATENTS nuclei. The resultant dispersion is expanded by a diverging tail 3,126,155 3/1964 Lohse ..239/14 Ofthe A f l "wumed around *F 3,313,487 4/1967 Merrill cool air into the expanding dispersion. A diverging tail portion 3,362,915 H1968 Micek H on the housing deflects outwardly the air flowing along the 3,429,507 2/1969 Jones 7 3,545,677 12/1970 Power et al. ..239/2 R 7 Claims, 3 Drawing i 2 Q 42 ii f 41 1H i i 46 in ii 1W 1' iii 5 5 51 33 W I! it o L1 in, 1 \w 24 ,1, r g o 26 2a U 28 54 1] 11 n til i 1 i iii Patented Feb. 29, 1972 INVENTOR Bradley T Patten AGENT ARTIFICIAL ICE NIJCILIEI GENERATOR LICENSE The invention described herein may be manufactured and used by or for the Government of the United States of Amer' iea for all governmental purposes without the payment to me of any royalty.

BACKGROUND OF THE INVENTION This invention relates to artificial ice nuclei generators (also known as cloud-seeding generators), and more particularly to a generator that provides high nuclei output with high efficiency, and that operates reliably with a minimum of maintenance.

These generators, which are usually flown on aircraft wings, burn a fuel containing artificial ice nuclei material. The fuel commonly is acetone, the material a silver iodide-sodium iodide complex. The complex vaporizes and then nucleates into particles. These particles are artificial ice nuclei" that can precipitate moisture from clouds and fogs. The ultimate particle sizes, which are critical, are controlled by the combustion and subsequent air quenching temperature-time profiles. If the combustion temperature is not controlled, the particles may deposit on the burner walls and ignition. This sediment reduces the burners efficiency and requires frequent maintenance. If the air quenching is not controlled, the particles are underor oversize and thereby reduce the seeding efficiency.

SUMMARY OF THE INVENTION This invention effectively overcomes the sedimentation and coagulation problems suffered by prior generators. Briefly this is accomplished by arranging the paths and temperatures of the air and gases flowing through the generator so that these problems are avoided.

BRIEF DESCRIPTION OF THE DRAWING FIG. l is a longitudinal cross-sectional view of one embodiment of the invention.

FIG. 2 is an enlarged cross-sectional view taken on line 22 of FIG. 1.

FIG. 3 is a longitudinal cross-sectional view of another embodiment of the invention.

DESCRIPTION OF THE EMBODIMENTS The generator I shown in FIGS. 1 and 2 includes a generally cylindrical combustion chamber 12 that has a nose cone I4 mounted in its left or inlet end. The nose cone has a number of evenly spaced openings or apertures 16 (see FIG. 2) that admit combustion air into the chamber 12 when the generator is flown through the air (or when air is forced through the stationarily mounted generator by a fan, not shown). The nose cone 14 also has a number of evenly spaced, elongated, peripherally extending cutouts 18 in its basal edge which admit a sheathlike flow of air along the inner wall 119 of the chamber when the generator and air are moved relative to each other. This boundary layer airflow cools the chamber wall 19 and sweeps out any particles that might otherwise deposit on the wall.

The nose cone cutouts 18 define radially extending tabs 20 that are bent to conform to the chamber I2 and then secured to the chamber, as by screws (not shown). The nose cone I4 should be mounted within the chamber inlet so that the cone s basal edge is spaced an appreciable distance d from the chambers front edge. This spacing, which controls the amount of air admitted into the chamber, should be adjusted to the aircrafts intended airspeed. For example, d should be increased from about three-fourth inch at 150 mph. to about 1% inch at 250 mph, for a 4-inch diameter combustion chamber. This adjustment maintains a constant position and quality of the flame in the chamber.

Mounted in the apex of nose cone I4 is a fuel injection nozzle 22 that sprays fuel 24 containing artificial ice nuclei material into the combustion chamber. The fuel, for example an acetone solution of a silver iodicle-sodium iodide complex, is supplied to the nozzle 22 from a fuel pump or pressurized tank (not shown) by a tubing 23.

The resultant fuel-air mixture is ignited momentarily by a spark plug or ignitor 26 mounted in the chamber; the ignition is then maintained by a glow plug 23 also mounted in the chamber. The electric currents for these plugs are supplied by conventional supplies (not shown) that are carried, for example, aboard the aircraft on which the generator 10 is mounted. The glow plug may simply consist of a thin-walled stainless steel cylinder that quickly attains a cherry glow.

The combustion chamber 12 terminates in a rearwardly converging conical choke portion 30 that maintains a uniformly high temperature in the chamber. This controls the vaporization of the silver iodide'sodium iodide complex so that the material does not deposit on the chamber wall I9. The previously described boundary layer airflow provided by the slots 18 of course aids in preventing any deposit. The combination of these elements greatly reduces the maintenance requirements of the present invention, as compared to prior generators.

A generally cylindrical shell 32 is spaced from and mounted on the combustion chamber 12 by means of several thin struts 31. This shell ducts the incident air (ram air) over the combustion chamber and thereby preheats the air. The amount of ducted air is controlled by a forwardly converging conical ring 33 that projects forwardly of the shell 32. The hot air mixes with the combustion chamber exhaust in a rearwardly converging conical portion 34 of shell 32. This heat chamber 34 is thermally insulated, as by a dead-air space 35. This arrangement controls the quenching of the nucleating particles of silver iodidesodium iodide complex so that the particles have sizes within an optimum range, neither too large nor too small. The generator thus burns the acetone solution more efficiently than prior generators.

The shell 32 terminates in a rearwardly diverging conical tail portion 36 that allows the effluent from the heat chamber 34 to expand as it leaves the generator and mixes with the atmosphere. This expansion reduces the chances that the quenched particles dispersed in the effluent gas (admixture of preheated air and exhaust gas) will coagulate into oversize particles.

A generally cylindrical housing 42 is spaced from and mounted on the shell 32 by thin struts 41. This housing, which ducts ram air over the shell 32, terminates in a rearwardly diverging tail portion 46 that extends over the shell tail portion 36. This arrangement ducts diverging cool air into the expanding dispersion and thereby further expands and dilutes the dispersion. In addition, the housing tail portion 46 outwardly .deflects the airstream flowing along the housing. The

airstream therefore does not interfere with the expansion of the diluted dispersion of silver iodide-sodium iodide particles. In this way the particles are thoroughly dispersed into the atmosphere.

FIG. 3 shows an embodiment 50 of the invention that is similar to the embodiment It) shown in .FIGS. 1 and 2, except that the tail portion 36 of shell 32 is elongated and is provided with several circular rows ofevenly spaced openings 38. Also, the diverging tail portion 46 of housing 42 extends over only a small end portion of the shell tail portion 36. This arrangement permits some of the cool ram air ducted by the housing 42 to bleed through the openings 38 and dilute the expanding dispersion.

In operation, the above-described embodiments of the invention are mounted on aircraft wingtips and flown through a cloud or fog whose moisture is to be precipitated, or are mounted on the ground and operated by a fan. The fuel 24 is injected into the combustion chamber from the nozzle 22 and is ignited at first by the ignitor 26 and then by the glow plug 28. Ram air is admitted by the cutouts I8 to prevent the resultant vaporized material from sedimenting on the chamber wall and the plugs 26, 23. The nucleating material is maintained hot by the chamber choke portion 30. Ram air is also ducted along, and heated by, the combustion chamber and used to quench the particles in the insulated, choke portion 34. The resultant dispersion is expanded by the tail portion 36; in the second embodiment some additional ram air is bled into the dispersion. Finally, ram air is ducted by the housing 42 over the shell 32 and is used to dilute the expanding disper sion.

lclaim:

1. An artificial ice nuclei generator comprising:

a generally cylindrical combustion chamber having an inlet end and an outlet end;

a nose cone mounted in said inlet end of said combustion chamber, said nose cone having a plurality of apertures in its conical surface and having a plurality of elongated, peripherally extending cutouts in its basal edge;

fuel injection means mounted in the apex of said nose cone for injecting fuel containing artificial ice nuclei material into said combustion chamber;

ignition means mounted in said combustion chamber for igniting the fuel-air mixture therein;

said outlet end of said combustion chamber terminating in a rearwardly converging conical choke portion;

a generally cylindrical shell spaced from and mounted about said combustion chamber, said shell having a thermally insulated, rearwardly converging portion extending rearwardly of said combustion chamber and terminating in a rearwardly diverging conical portion; and

a generally cylindrical housing spaced from and mounted about said shell, said housing terminating in a rearwardly diverging conical portion.

2. A generator as set forth in claim 1, and means for supplying said fuel containing artificial ice nuclei material to said fuel injection means.

3. A generator as set forth in claim 1, said ignition means including spark plug means for initiating the ignition of said fuelair mixture and glow plug means for sustaining said ignition.

4. A generator as set forth in claim 1, said basal edge of said nose cone being positioned rearwardly of the front edge of said chamber inlet.

5. A generator as set forth in claim 1, said shell having a forwardly converging conical portion extending forwardly of said combustion chamber.

6. A generator as set forth in claim 1, said housing having a rearwardly converging conical portion extending about said heat-insulated, rearwardly converging conical portion of said shell.

7. A generator as set forth in claim 1, said rearwardly diverging portion of said shell having a plurality of apertures in the conical surface thereof. 

1. An artificial ice nuclei generator comprising: a generally cylindrical combustion chamber having an inlet end and an outlet end; a nose cone mounted in said inlet end of said combustion chamber, said nose cone having a plurality of apertures in its conical surface and having a plurality of elongated, peripherally extending cutouts in its basal edge; fuel injection means mounted in the apex of said nose cone for injecting fuel containing artificial ice nuclei material into said combustion chamber; ignition means mounted in said combustion chamber for igniting the fuel-air mixture therein; said outlet end of said combustion chamber terminating in a rearwardly converging conical choke portion; a generally cylindrical shell spaced from and mounted about said combustion chamber, said shell having a thermally insulated, rearwardly converging portion extending rearwardly of said combustion chamber and terminating in a rearwardly diverging conical portion; and a generally cylindrical housing spaced from and mounted about said shell, said housing terminating in a rearwardly diverging conical portion.
 2. A generator as set forth in claim 1, and means for supplying said fuel containing artificial ice nuclei material to said fuel injection means.
 3. A generator as set forth in claim 1, said ignition means including spark plug means for initiating the ignition of said fuel-air mixture and glow plug means for sustaining said ignition.
 4. A generator as set forth in claim 1, said basal edge of said nose cone being positioned rearwardly of the front edge of said chamber inlet.
 5. A generator as set forth in claim 1, said shell having a forwardly converging conical portion extending forwardly of said combustion chamber.
 6. A generator as set forth in claim 1, said housing having a rearwardly converging conical portion extending about said heat-insulated, rearwardly converging conical portion of said shell.
 7. A generator as set forth in claim 1, said rearwardly diverging portion of said shell having a plurality of apertures in the conical surface thereof. 